Research Of Gas Monitoring System Based On Chemical Porphyrin Sensor

Since the beginning of the 20th century, with the progress of science and technology, the variety of chemical substances grows rapidly at the annual rate of nearly 1000 kinds. Modern industrial, township enterprises and private enterprises develop rapidly, which brings economic prosperity but also serious environmental pollution and social problems. Harmful gases endanger human health severely, so the design of accurate, effective, convenient gas detector for people's life and work is of great significance.This paper summarized the advantages and disadvantages of the existing gas detection systems based on the current up-to-date chemical and electronic technology, innovatively proposed a porphyrin-based chemical gas sensor detection system, in which harmful substances in the atmosphere was pumped into the pre-designed chamber and acted with the porphyrin sensor, then the response before and after the color change of the sensitive spots of the porphyrin sensor was captured by CMOS image sensor array. At last, the color change was compared to the records in the fingerprint database to get the final detection results. In this way harmful substances to human health in the gas can be detected rapidly and effectively. The system can be widely used in industrial exhaust gas detection, harmful gases detection in the atmosphere, as well as home environment, and improve the living environment of mankind, as well as human health, so it is of great practical significance.In this paper, the characteristic study completed are as follows:1. Hardware circuits was designed using ARM9 + MCU. With the idea of modular design, Samsung's S3C2440 chip ARM9 processor was chosen as the core hardware systems, with peripheral circuits including the LCD touch screen display circuit, image acquisition circuit, SD card memory circuit, a serial communication circuit and communication circuit and USB interface. Microchip's PCI16F877 worked as a secondary control system MCU, with peripheral circuits including the air pump drive control circuit, the reaction condition detection circuit, control circuit and alarm circuit of serial communication. Finally communication between ARM9 and the MCU was implemented by serial interface conveniently.2. System software was designed based on the open source embedded Linux operating system and Microchip's MPLAB IDE V8.00. In the Linux operating system, the LCD Touch Panel Module device driver design, SD card storage device driver design, the camera device driver interface design was completed; the MCU control procedures (including the pump speed control, alarm devices, as well as temperature and humidity control flow signal acquisition) was completed in the environment MPLAB IDE V8.00;Real-time image acquisition, display and storage for chemical sensor array, as well as the impact factor of chemical reaction dynamics of the acquisition and control was implemented.3. The gas detection system was designed and assembled in accordance with the hardware equipment size and mechanical properties by AUTOCAD and used to detect NH₃, acetone and ethane experimentally.In order to further improve the system and make the study go on, a self-evaluation was given in the summary of the paper. Some views for the future development direction was also put forward.